Apparatus for treating metal



Jan. 2, 1968 w. T PURVANCE APPARATUS FOR TREATING METAL 2 Sheets-Sheet 1Filed April '2, 1965 taut [/Vl/E/VfOR W/LL/AM r PURVANCE y W Af/a rneyJan. 2, 1968 w T. PURVANCE APPARATUS FOR TREATING METAL 2 Sheets-Sheet 2Filed April 7, 1965 lNVE/VTOR W/LL/AM 7T PURVA/VCE United States Patent3,360,974 APPARATUS FOR TREATING METAL William T. Purvance, Pittsburgh,Pa., assignor to United States Steel Corporation, a corporation ofDelaware Filed Apr. 7, 1965, Ser. No. 446,223 2 Claims. (Cl. 72-,224)

ABSTRACT OF THE DISCLOSURE A rolling mill adapted to perform drasticreduction of metal work of 50% or more in a single pass from ingot andbillet sizes which includes a nest of four work rolls having axes atright angles to each other and which form a fully confined pass for theWork. Each roll is motordriven and is supported in its oWn housing andan adjacent housing. The mill also contains removable capping means foreach roll which maintain the roll shafts in the mill housing and can beremoved for roll replacement.

This invention relates to an apparatus for treating metal. Moreparticularly, the invention relates to a rolling mill especially usefulfor drastically reducing the cross-section of steel shapes. Ofparticular benefit, is the use of the apparatus in so-called single passrolling of closely controlled cross-sectional areas. In such rollingprocesses, the metal is brought to the desired cross-sectional area in asingle pass through the rolling mill. The invention is particularlyadaptable to processing continuously cast steel, although it is alsouseful and adaptable to conventional rolling of shapes in vertical orhorizontal rolling mills. In addition, the drastic reduction in crosssection which is possible with the invention produces a metallurgicalstructure in the rolled work unlike that which results from conventionalrolling practices. That is to say, the product possesses an elongatedgrain structure more similar to metallurgical structures of extrusionsand forgings than of conventionally rolled material.

In continuous casting of steel, the most common technique is to pourmolten metal into a water cooled mold at a closely controlled rate. Theshape of the water cooled mold controls the size of the cast steelcolumn. The molten steel at the exterior surface is solidified in thecooling area of the mold and the steel column emerges from the mold,usually in a downward direction. From the mold, the steel column entersa pair of pinch rolls which control the rate of descent. Generally, thepinch rolls contact only two sides of the cast bloom and can only reducethe cross-sectional area to the extent that it is necessary to createenough friction to support the weight of the steel above it. Such rollscannot be used to substantially reduce the cross-sectional area of thesteel because of the unprotected and unsupported areas where the steelwould bulge and distort on the sides of the steel column not in contactwith the rolls.

The present invention avoids the above disadvantages and others byproviding a nest of rolls which support and protect the steel column onall sides. Moreover, the design of the novel rolling mill enables it towithstand severe rolling forces and therefore to perform drasticreductions in cross-sectional areas in a single pass. According to thepresent invention, an apparatus is provided which employs four rollsdisposed at substantially right angles to each other and with abuttingroll faces. In the preferred embodiment, each of the rolls have taperededges beveled at 45 and are arranged so that adjacent beveled faces abuteach other. Each of the rollers are supported by a shaft extending fromeach end of the roll which in turn rests in and is supported byindividual mill housings in a manner to be hereinafter described. Thenovel design of the mill also permits the rolls to be quickly and easilychanged, as needed, with minimum shut-down time.

The use of the invention in conjunction with continuous casting permitsa large cross-sectional area to be cast in the casting mold, e.g., 24 x24", and due to the rigidity and strength of the rolling mill as well asits novel design, such large cast shapes may be drastically reduced in asingle pass of the metal through it to, for example, a 12" x 12" billet.Because of this ability, two mills of my design, one as a following milllocated beneath the first mill, can be used to effectively reduce in asingle pass a large cast ingot of, for example 24" x 24", to a billet assmall as 4 x 4". One of the handicaps of continuous casting processlines has been the limitation on the continuous casting rate broughtabout by the limited rate of descent of the steel through the castingmold; thus, for example, if only small billets, i.e., 4" x 4", can becast, a limited production is obtained. This is due of course to thefact that metal cannot be withdrawn from the mold any faster thansolidification takes place. However, by use of the invention, billets ofthe same size, i.e., 4" x 4", could be produced at a rate 36 timesfaster than the casting rate of the 24 x 24" steel column. Moreover, myrolling mill, besides performing the function of pinch rolls to controlthe rate of descent and substantial reduction in the size of the caststeel column, also has the effect of equally distributing the heatthroughout the cross-sectional area of the bloom and thereby provides aforged or extruded grain type product which is presently obtained onlyby costly processing.

Other advantages and features of the invention will become apparent inthe following description taken in conjunction with the drawings whichillustrate various embodiments of the invention.

In the drawings:

FIGURE 1 is a plan view in horizontal section through the bearingsshowing an assembly of a nest of rolls in accordance with the invention;

FIGURE 2 is a sectional view taken along the line IIII of FIGURE 1showing the arrangement of mill housings and rolls;

FIGURE 3 is a sectional view taken along lines III- III of FIGURE 1showing the arrangement of the housing, roll shafts and bearing inserts;

FIGURE 4 is a schematic view of a typical rolling mill in accordancewith the invention illustrating how it may be used in continuous castingprocesses; and

FIGURE 5 is a schematic view showing how the invention can be readilyadapted to permit rolling of various shapes.

As shown in FIGURE 1, four rolls 13a, 13b, 13c and 13d are arranged toform a nest of rolls with the axes of the rolls at substantially rightangles to each other and with abutting roll surfaces forming a fullyclosed pass for the Work 11. Each of the rolls has a primary shaft 15a,15b, 15c and 15d and a secondary shaft 17a, 17b. 17c and 17d extendingfrom opposite sides of the rolls 13a, 13b, 13c and 13d respectively.Associated with each roll is a mill housing 19a, 19b, 19c and 19d whichsupports the primary shaft of that roll. Thus, mill housing 19a supportsthe primary shaft 15a of roll 13a; similarly. mill housing 1% supportsthe primary shaft 15b of roll 1317, etc. Within each mill housing is arecess 21a, 21b, 21c and 21d which receives the secondary shaft of an adjacent roll. Thus, for example, mill housing 19a receives in the reccess21:: the secondary shaft 17d of roll 13a while mill housing 19b receivesat 21b the secondary shaft 17a of roll 13a. The secondary shaft 17b isfitted into the recess 210 of mill housing 190 associated with roll 130.Secondary shaft is received by the recess 21d of mill housing 1%. Theprimary shafts 15a, 15b, 15c and 15d of each of the rolls are preferablyindependently driven and are equipped with independent but synchronizedmotor drives.

Suitable capping means 25 (best shown in FIGURES 2 and 3) maintain theroll shafts in the mill housings. The capping means 25 may be a singlelarge cast section; however, in the preferred embodiment comprises a top27 and inserts 29 which extend into the mill housings to hold the rollshafts in position. The use of separate capping means in this mannerpermits the rolls to be changed easily by use of an overhead crane whichremoves the cap and inserts from the mill housing after which the rollscan be removed from the housings and new rolls positioned to replacethem. The mill housings 19a, 19b, 19c and 19d may be mounted onconventional housing shoes 18 to which they are attached, as by capscrews 16. In this way, the mill housings are held rigidly in place atthe bottom. It will be observed that with the above described design themill housings are not subjected to any cross strains since all rollingforces are directed in the same manner against housings.

Upon metallurgical examination of a drastically reduced product producedfrom this rolling mill, the prodnot will be found to have a greatlyelongated grain structure. Moreover, the product will have a greaterhardness than conventionally rolled material.

The configuration of the working surface of the rolls 13a, 13b, 13c and13d is made to conform to the desired cross-sectional area of the finalproduct. In the embodiment shown in FIGURE 1, the faces of the rolls aremachined to provide a square product. This is accomplished as shown byusing rolls with beveled edges 20 having a 45 taper at the edges of therolls. When the rolls are arranged as shown with adjacent edgesabutting, a fully closed pass for the work is provided. Furthermore,lateral movement of each roll is precluded by the support provided byadjacent rolls. The roll shafts a, 15b, 15c and 15d, which are supportedon bearings 23a, 23b, 23c and 23d, are individually connected withconventional motor drives and couplings to provide the force necessaryfor the drastic reduction of steel shapes. The bearings, which may be ofthe friction or anti-friction type allow free rolling of the rolls.However, because of the friction that results from the closely machinedtapered faces of each of the rolls and the force of the crosssectionalarea during rolling, it is possible to drive the mill with a singledrive. The nest of rolls which are arranged to provide a fully closedpass for the work form a funnel into which hot steel can be inserted andwhich emerges at the exit side of the mill with the exact circumferenceand configuration of the work roll faces.

It should be noted that the rolling mill of the invention can be easilyadapted to a continuous casting line. As an example, two nests of rolls,30 and 40, which are of the design described in FIGURES 1, 2 and 3, maybe positioned as shown in FIGURE 4 to receive a hot poured ingot frommold 35. The primary mill reduces the cross-sectional area of the caststeel column 37. The steel of reduced section 39 leaving primary mill 30can be passed into a following mill 40 where it emerges with a stillsmaller cross-sectional area. Obviously, additional mills can beprovided to accomplish further reduction as desired or a single mill maybe used if less reduction is needed.

In addition to use in a continuous casting line, the invention may beemployed as horizontal rolling mills for blooms, bars, billets or othershapes. This is accomplished in the same manner as heretofore describedexcept that the mill is built for a vertical pass. By altering theworking face of the rolls, as shown in FIGURE 5, squares, rounds,hexagons or other shapes can be produced. Through the use of successivemills of this design, i.e., following mills, very great reductions ofthe original work may be performed. By using work rolls with closelymachined edges beveled at and driving the four rolls so they rotate tothe center at the same speed, friction is minimized. All four rolls maybe synchronized in speed through mechanical linkages or electricalcircuitry.

I claim:

1. A rolling mill adapted to perform drastic reduction of metal work ofor more in a single pass from ingot and billet sizes such as to producean elongated grain structure characteristic of extrusions, said millcomprising a nest of four work rolls arranged with their axes atsubstantially right angles to each other and with abutting roll surfacesforming a fully confined pass for the work, a motor and drive for eachwork roll, a primary and a secondary shaft extending from opposite sidesof each of said work rolls, a mill housing for each work roll supportingthe primary shaft of that roll, means within each mill housing a supportsecondary shaft of an adjacent work roll, and removable capping meansassociated with each roll for maintaining the roll shafts in the millhousings and which when removed permit replacement of the rolls in thehousings.

2. A rolling mill according to claim 1 in which the edges of the rollsare beveled at 45 and the rolls are positioned with abutting beveledsurfaces such that together the rolls form a fully confined pass for thework.

References Cited UNITED STATES PATENTS 281,978 7/1883 Crandell 722241,788,693 1/1931 Stiiting 72224 1,994,187 3/1935 Bennington 72-224CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,360,974 January 2, 1968 William T. Purvance that error appears in theabove numbered pat- It is hereby certified d that the said LettersPatent should read as ent requiring correction an corrected below.

Column 1, line 69, for "rollers" read rolls column 2, line 66, for "13a"read 13d Signed and sealed this 4th day of February 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, 11'.

Attesting Officer

